The Lake is a Location in Fear & Hunger 2: Termina. It is the western bank of the Sacrificed Waters (Bohemian: Obětní Jezero lit. "Sacrificial Lake"), a large body of water bordering Prehevil.
Marina: "The lake is called 'The sacrificed waters'..."
Marina: "Its murky depths have always freaked me out a bit, even before I understood the meaning of its name."
Marina: "Trust me, you don't want to know the meaning."
Trivia
Judging by Levi and Marina's reactions, it is likely the lake was literally used for human sacrifice.
Newspaper article similarly mentions the lake Lake Verdite to be just east of Prehevil. However, it is unconfirmed whether Lake Verdite and the Sacrificed Waters are indeed the same lake.